Plug gauge



Oct. 10, 1950 A. MANVERS PLUG GAUGE Filed Aug. 4, 1947 i atenteel ct. 1 0,

Application August 4, 1947, Serial No. 766,115

In Great Britain February 16, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires February 16, 1963 .3 Claims. (01. 33-162) This invention relates to plug gauges of the type wherein a tapered plug is adapted to slide axially between a pair of gauge blocks mounted thereon diametrically oppositev one another to provide by their exterior surfaces gauge faces, the said blocks being constrained to close on the plug by spring means and to be expanded by moving the plug therebetween in the appropriate direction.

The object of this invention is to provide an improved construction of gauge of the type above defined. I

In order that the saidinvention may be readily understood reference is directed to the following description of an embodiment which is illustrated by the accompanying drawing which shows the gauge in part sectional side elevation. In the embodiment illustrated the plug I is adapted to slide between a pair of diametrically opposite blocks 2 and alternatively force them to expand or allow them to contract together, the manner in which these blocks are mounted being as follows. The aforesaid plug I has an elongated slot 3 running along a suitable portion of its length and mounted through the slot is a stud 4 which in turn passes through lapped holes 5 in the blocks 2, and by having springs 6 set in counterbored holes leading from said lapped holes 5 and providing nuts I at each end of the stud, it will be seen that the stud 4 with its nuts 'I at each end holds the two blocks 2 together with the springs 6 forcing the blocks to grip the surface of the plug The inner surfaces 8 of the blocks which grip the plug I are V-shaped to saddle on the plug whilst the outer surfaces 9 are slightly cambered or radiused in a transverse direction.

To measure the diameter of any bore, the plug is first moved so that the blocks are at the small end of the taper, and are therefore contracted together as much as possible. The whole assembly is then placed within the mouth of the bore and the plug is moved in the opposite direction so that the tapering forces the blocks to expand until their cambered outer surfaces 9 nicely engage the interior surface of the bore. It will be apparent that the distance between the two outer surfaces of the blocks will give a true reading of the diameter of the bore, and once the blocks are in this position, the whole gauge may be withdrawn from the bore without fear of movement of the blocks, as the springs hold them firmly on to the plug. Also, by moving the gauge along the interior of the bore once the reading for the diameter has been obtained, it

2 is possible to check if the bore is parallel throughout its entire length.

Running longitudinally through the centre of .the plug I there is a bore II which extends in length from the widest end of the plug to a point I2 just beyond the far end of the slot 3. Suitably. disposed in the aforesaid bore is a threaded spindle I3 having an eyed-end I4, and

through this eye there passes the stud d which links the blocks 2 together, whilst theother end of the spindle projects out from the bore beyond the widest part of the plug. The plug is free to slide on the spindle [3. At the aforesaid broad end of the plug there is a circumferential flange I5, and that section of the centrally disposed bore II which passes through the flanged end is of enlarged cross-section, so that this particular end of the plug is formed with a socket I6. On to the projecting end of the eyed-spindle I3 there is threaded an actuating nut IT with a projecting spigot I8 which snugly engages in the socket I6 of the plug I. The actuating nut IT although capable of being rotated on the spindle I3 is held firmly in the aforementioned socket I6 against axial movement by a circumferential groove I9 around the spigot I8 which is tangentially engaged by two pins 20 which pass through the body of the flanged end of the plug I. The groove and pins thus lock the plug and actuating nut together so that no matter in what direction the actuating nut is rotated the plug gauge moves with it, and since also the blocks are linked to the eyed-spindle it will be apparent that as the plug and actuating nut travel along this spindle the plug will either expand the blocks or cause them to contract. Thus the method of measuring a bore is the same except that the plug is moved between the blocks byan actuating nut. A lock-nut 2I may also be provided and is of an elongated form so as to cover the projecting end of the eyed-spindle.

Graduations may be marked suitably on the guage; for example, the fiat face I5a of the plug may have a circular scale of diameters assumed between the gauge faces of the blocks, and the actuating nut provided with an indicating arrow which registers with the graduation corresponding to the adjusted diameter of the blocks.

I claim:

1. An expansible plug gauge comprising a tubular, generally conical plug having a longitudinal slot, a pair of diametrically aligned blocks and each having an outer work-engaging cylindrical face and an inner inclined face engageable with the outer surface of the plug, a

3 stud extending through the slot and having end portions each slidable in a block at right angles to the said outer face thereof, said stud constituting the sole means for laterally supporting and guiding the diametrally opposed blocks in alignment, spring means each reacting against the stud and urging a block to plug-engaging position, a screw extending within the plug and held against rotation by the stud, and a nut threaded on the screw and connected to the plug and upon rotation moving the screw, stud and blocks in either direction.

2. The plug gauge according to claim 1 and wherein one end of the screw has an eye receiving the stud.

3. An expansible plug gauge comprising, a tubular conical plug having a bore and a longitudinal slot communicating with the bore of the tubular plug; apair of elongated substantially thin blocks disposed entirely exteriorly of said plug and extending therefrom in wing-like formation in diametral alignment, each block having an inner inclined face with a V-shaped longitudinal groove therein iorsaddle-like engagement with the tapered exteriorsurface oi the plug, an outer work-engaging cylindrical face disposed parallel to the longitudinal axis ofsaid plug and an opening extending through the thickness of the block from the inner face to a counterbored recess in the outer face thereof; a captive nut element rotatably attached at the mouth of the plug bore at the larger endof said plug; a threaded spindle threading through said the" diametrally opposed blocks;

captive nut and extending into the plug bore to terminate in an eye; a lock nut screwthreaded on an exteriorly projecting portion of said spindle to lock said spindle in a required position of endwise displacement relative to said plug; a stud passing through the spindle eye and the plug slot and slidable in the openings of the diametrally aligned blocks, said stud having enlarged head portions on the opposite ends thereof which lie within the counterbored recesses of and springs interposed between the undersides of said stud head portions and the inner end of the counterbored' recesses to urge the blocks inwards to maintain contact with the plug.

ANTHONY MANVERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS;

Number Name I Date 1,476,681 Bath et a1. Dec. 11, 1923 1,478,541 Bath Dec. 25, 1923 1,511,934 Bath Oct. 14, 1924 1,579,334 Poncet g Apr. 6, 1926 2,135,912 Rae Nov. 8, 1938 FOREIGN PATENTS Number Country Date 148,574 Great Britain July 10, 1920 554,054 Great Britain June 17, 1943 

